Roll of adhesive tape



Sept 8, 1953 D. w. ENGBERG EI'AL 2,651,408

- ROLL OF ADHESIVE TAPE Filed Aug. 15, 1949 I NVENTORS DONALD W ENGBERG WALTER A. NORTON Q T M,m., M 2% ATTORNEYS Patented Sept. 8, 1.953

ROLIJOE ADHESIVE TA-PE Donald Engb'el'g', St. Paul; and Walter AtNor ton; MahtomedL Minn assignors to Minnesota Mining.i&.Manufacturing Company; St. Paul Minn=,,.;a.-.corpora-tion of Delaware.-

AppliatihnAugusflS, 1949; Serial No; 110,312"

This invention is concerned with normally" tacky and pressure-sensitive adhesive tape; par-- strip roll form wherein the contiguous strips arefirmly but detachably inter-connected.

Strong, heavy fibrous adhesive tape is" customarily applied as a reinforcement to the'thinleather:- of shoe uppers at thebackof'the areadesignatedi for insertion of the lacingeyelets. Normally tacky and pressure-sensitive adhesive tape designed for-thi'spurp'ose has become known as eyelet? staytape? suchapplication, in dividual tape sectionsmaybe cut from a roll and applied' to thework as:they are -cut. A more efiicient' method is I to; pre-cuta number of strips to; the: exactflsize requiredb The strips-may then beaapplied: in the usual way; Cutting of the strips-:from a, single roll of tape is '-tiine'-consuming; and" inaccurate; and in: anylarge-scale op-- eration requires frequent replacing of' rolls.- Multiple-striproll's inwhich each separate strip partially overlaps the backing of the next ad-- jacentzstrip" have Joeen suggested; as providin'ga relatively: large-number ofiid'entical sectlon's with' aESiIlgIGE-CHttiIIE-QJOfiCII but such =rolls are difllcult' to wind, do not unwind smoothly; and areumnecessarilyslarge' in diameter. Another'suggested system' involves" placing partly or" wholly sep-- parated; sections zof the: tape' on" a liner or slip sheeting-1 from' which indl 'v-idual sectionsmay later: be: removed as needed; The liner is then discarded; which-1 representsawasteful" and uneeonomicallpractice:

lit-is: therefore an object 'of the present" invention-to provide afibrous adhesive tape-productinrol-llform whichiavoids the-*dcfectsanddisadvanftagesi of. prior: art products and methods: A

more: specific. obj ecti's to providea' roll -'ofadhe venient size, from which portions individual ac curately: sized pieces or section's of tape may be readilydetached needed.-

T-heinvention will bemore readily understood by reference to the accompanying drawing, showing in perspective an exemplary roll of the adhesive-coated fibrous sheet material, from the The. mixturev forms a: substantially continuous.

1"; Claim'a. (Cl. 206*56) tionship is maintained duringi unwinding: of the:

composite: sheet and also whenza.terminalfitransaverse portion I5 iscut off-2'. 'Ihis;l'attiersportion: may then conveniently be?hand le'da.as. unit}: the individual sections I fii thereofi biein .li'eld" to:-'- gether by'the narrowsconnectingrarease. 1.. Howlever, when an individual-"section:l8of thettap required, itis easily: detachedcfromttliesnml-tiple strip segment l.5 by; breaking: the narrow conenecting. areas, as shown. atzl 9:

One specific adhesive; taper productiwhichizhast been found acceptable as ran.eyelemstay-tapefior" shoes is made in accordance with the following. example. A thicle. porous creped paper; having a multidirectionat stretch; characteristic; obe tained by a double:crepingpoperatioricwitkt two; sets of crepingzi lines-s at right-.-. angles list; se'- lectedi as the-back-ingLt Therpapeir has naa parent thickness of: about: 1'7? mils; aindlbases weight of lbs; per 32.0vsq: ydszz. Ita'szfirst coated-i on the back. side: with aboutaiifl-KSTgrams: perrscp. yd. of a low-adhesion; b'acksiZe: co-mposition, .ap'- plied from solution 1m as mixture; of: tworv parts: xylol and one-part: butylzalcoholz. 'I.'h backasize composition. consists :of; four: parts oi'zi polys vinyl butyral resin',.two;' parts:- of: hydrogenated; castor oil (castorewax), andiomazpartioffstearic1 acid, blended together; at: an: eleyatedti temperatture inthe presenceofi.1--2;%;- ofzatrubbert ant e oxidant, e. g. para+hydroxy=phenyl=morpholin coating; on. the: surfacei of the paper; and-E also: penetrates partcwayiinto thesweo- The backing, is then; coatedi. cm the? unooated or" face side with wwatereinsoluble}: normally-'- tacky and pressure--sensitiveadhesive' ofthefruifi her-resin? type; e: g. a;-blend ofil0'0 parts of=crude*- rubber; 50 parts of zincioxid pigment, I'OO partS of wood rosin, and 12 *p'arts*of 'anantioxidantj applied from solution khan-amount-of heptane suificient to impart asuitable coatingviscosity? A total weight of about"225' -250 'grams per'sqt yd? of the dried adhesive efi'ective"impartially-fin pregnating the backing and forming a uniform, adherent surface coating. The sheet as thus prepared may be wound up on itself in roll form and unwound therefrom without delamination or offsetting of the adhesive.

The coated sheet is next converted to the multiple-strip roll form illustrated in the drawing, by passing the web between a row of notched circular slitter knives and a hardened metal score roll. The knives; are radially sawed or notched at equal distances around their circumferences and to an extent such that the web is alternately slit for about inch, then left unslit for about /54, inch or slightly less. After slitting,.the .tape is wound up on a core to provide a roll of contiguous and partially connectedistrips of tape, as shown in the drawing. i

The above example represents one specific embodiment of the invention. A number of equivalent structures will be apparent to those skilled in the art on consideration of thedescription and teaching appearing herein, and all such equivalents coming within the scope of the invention and the appended claim are contemplated. Fibrous paper backings may be used which vary considerably from that hereinabove specifically described in weight, caliper, porosity, type of fiber, --fiexibility and stretchability, and other characteristics, and such backings are believed to be well-known in the shoe-findings art. Equivalent non-woven fibrous webs other than true paper, e. g. short-fibered cotton wadding, may be used. Shellac, cellulosic esters of higher fatty acids, blends of alkyd and urea-formaldehyde resins, and other known low-adhesion backsize compositions may replace the particular composition of the above example, either as a backsize or, in someinstances, as a partial impregnant also. The fibrous backing may initially be treated or impregnated for improved strength, water-resistance, or other properties, one suitable exemplary treatment consisting of a blend of rubber (or solubilized reclaimed rubber) and resin applied fromdilute solution in a volatile hydrocarbon solvent.

The adhesive may be one of the various rubberresin type pressure-sensitive tape adhesives, well known in the art, which are water-insoluble and aggressively tacky. One such adhesive is described in connection with the specific description appearing hereinbefore; others have been described in. previously issued patents; cf. U. S. Patents Nos. 1,760,820, 2,227,444, 2,236,527, 2,410,- '78, 2,410,089, 2,438,195. These adhesives have a rubbery base of natural or synthetic rubber which provides cohesion (internal strength) and elasticity (a retractive force when stretched and retraction when released after stretching) and this rubber base is modified by blending with a com patible tackifier resin (such as rosin or ester gum) which serves to increase adhesion (tackiness) and decrease cohesion, with an attendant increase of stretchiness (elongation under low stresses) and decrease of elasticity. Certain synthetic polymers inherently possess an equivalent four-fold balance of properties and can be used as pressuresensitive tape adhesives, thus being equivalents of the rubber-resin adhesives and hence they may be regarded as being of the rubber-resin type. An

example is a 75:25 copolymer of 2-ethyl-butyl-1 acrylate and ethyl acrylate.

As previously described, the preferred eyelet stay tape roll structure consists of at least six, and preferably about twelve, contiguous but separate strips of heavy fibrous adhesive tape detach- 4 ably held together by recurring narrow connecting areas of the fibrous backing, such areas representing only about 4% of the total longitudinal edge of the tape and being separated along such edge by about V inch. Surprisingly, it has been found that this small connecting area not only provides ample strength to withstand the stresses involved during winding and unwinding of the roll and during removal of the terminal portions IE, but also produces substantially no observable disruptionof the edge when the individual sections are detached. On the contrary, strips connected at less than about /2-% inch intervals,

e. g. at 4 inch intervals, are found to have an undesirable jagged and irregular edge when detached from the continguous strip, even though the width of the individual connecting areas is correspondingly reduced. Connections at intervalsmuch greater than about one inch are undesirable in the case of eyelet stay tapes, since the individual tape sections are usually of the order of x 1% inches and it has been found that at least two connecting points between two contiguous strips are desirable.

Within the limits of about /2-1 inch separation and about 3-8% connection, contiguous strips of fibrous adhesive tape such as the eyelet stay tape herein described are found to be adequately held together under all normal stresses incident to manufacture and handling, and to be readily detachable as desired for application. This result is believed to be partly due to the combination of the low-adhesion backsize, the fibrous backing, and the cohesive, normally tacky and pressure-sensitive adhesive. The low-adhesion backsize permits easy unwinding from the roll of a tape product havin desired highly aggressive tackiness toward leather and other surfaces. The fibrous backing resists tearing at the connecting areas during slitting and winding. The tacky adhesive tends to flow together at the continguous cut edges and. aids the connecting areas of the fibrous backing in maintaining the strips in side-by-side relationship.

Having now described various embodiments of our invention for purposes of illustration, but. without intent to be limited thereto, what we claim is as follows:

A roll of adhesivetapematerial comprising a flexible non-woven fibrous backing having a lowadhesion backsize and continuously coated on the face-side with a normally tacky and pressuresensitive adhesive of the rubber-resin type, wound 1 upon itself in roll form, and formed of at least six continuous lineal tape strips firmly but detachably held together in'side-by-side relationship by minute connecting areas thereof which are lineally spaced apart about /z1 inch, the said adhesive bridging the contiguous cut edges of adjacent strips of said backing to provide additional holding means between said strips.

v UNITED STATES PATENTS Number Name Date 454,316 Wheeler June 16, 1891 2,118,791 Hines May 24, 1938 2,170,147 -Lane Aug. 22, 1939 

